NOW® Coral Calcium Plus contains an alkaline form of Calcium that can help to support a healthy serum pH. In addition, Coral Calcium contains a number of trace minerals that are important for bone health, as well as for optimal enzymatic activity. NOW® Coral Calcium is not harvested from living coral reefs or even from the ocean environment, but from above-ground sources in Okinawa. In this Coral Calcium Plus formula, Magnesium and Vitamin D have been added because of their essential role in bone metabolism.*